import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

/*
 * ListDialog.java is meant to be used by programs such as
 * ListDialogRunner.  It requires no additional files.
 */

/*
 * Use this modal dialog to let the user choose one string from a long
 * list.  See ListDialogRunner.java for an example of using ListDialog.
 * The basics:
 * <pre>
 String[] choices = {"A", "long", "array", "of", "strings"};
 String selectedName = ListDialog.showDialog(
 componentInControllingFrame,
 locatorComponent,
 "A description of the list:",
 "Dialog Title",
 choices,
 choices[0]);
 * </pre>
 */
public class ListDialog extends JDialog
implements ActionListener {
	private static ListDialog dialog;
	private static String value = "";
	private JList list;

	/*
	 * Set up and show the dialog.  The first Component argument
	 * determines which frame the dialog depends on; it should be
	 * a component in the dialog's controlling frame. The second
	 * Component argument should be null if you want the dialog
	 * to come up with its left corner in the center of the screen;
	 * otherwise, it should be the component on top of which the
	 * dialog should appear.
	 */
	public static String showDialog(Component frameComp,
			Component locationComp,
			String labelText,
			String title,
			String[] possibleValues,
			String initialValue,
			String longValue) {
		Frame frame = JOptionPane.getFrameForComponent(frameComp);
		dialog = new ListDialog(frame,
				locationComp,
				labelText,
				title,
				possibleValues,
				initialValue,
				longValue);
		dialog.setVisible(true);
		return value;
	}

	private void setValue(String newValue) {
		value = newValue;
		list.setSelectedValue(value, true);
	}

	private ListDialog(Frame frame,
			Component locationComp,
			String labelText,
			String title,
			Object[] data,
			String initialValue,
			String longValue) {
		super(frame, title, true);

		//Create and initialize the buttons.
		JButton cancelButton = new JButton("Cancel");
		cancelButton.addActionListener(this);
		//
		final JButton setButton = new JButton("Set");
		setButton.setActionCommand("Set");
		setButton.addActionListener(this);
		getRootPane().setDefaultButton(setButton);

		//main part of the dialog
		list = new JList(data) {
			//Subclass JList to workaround bug 4832765, which can cause the
			//scroll pane to not let the user easily scroll up to the beginning
			//of the list.  An alternative would be to set the unitIncrement
			//of the JScrollBar to a fixed value. You wouldn't get the nice
			//aligned scrolling, but it should work.
			public int getScrollableUnitIncrement(Rectangle visibleRect,
					int orientation,
					int direction) {
				int row;
				if (orientation == SwingConstants.VERTICAL &&
						direction < 0 && (row = getFirstVisibleIndex()) != -1) {
					Rectangle r = getCellBounds(row, row);
					if ((r.y == visibleRect.y) && (row != 0))  {
						Point loc = r.getLocation();
						loc.y--;
						int prevIndex = locationToIndex(loc);
						Rectangle prevR = getCellBounds(prevIndex, prevIndex);

						if (prevR == null || prevR.y >= r.y) {
							return 0;
						}
						return prevR.height;
					}
				}
				return super.getScrollableUnitIncrement(
						visibleRect, orientation, direction);
			}
		};

		list.setSelectionMode(ListSelectionModel.SINGLE_INTERVAL_SELECTION);
		if (longValue != null) {
			list.setPrototypeCellValue(longValue); //get extra space
		}
		list.setLayoutOrientation(JList.HORIZONTAL_WRAP);
		list.setVisibleRowCount(-1);
		list.addMouseListener(new MouseAdapter() {
				public void mouseClicked(MouseEvent e) {
				if (e.getClickCount() == 2) {
				setButton.doClick(); //emulate button click
				}
				}
				});
		JScrollPane listScroller = new JScrollPane(list);
		listScroller.setPreferredSize(new Dimension(250, 80));
		listScroller.setAlignmentX(LEFT_ALIGNMENT);

		//Create a container so that we can add a title around
		//the scroll pane.  Can't add a title directly to the
		//scroll pane because its background would be white.
		//Lay out the label and scroll pane from top to bottom.
		JPanel listPane = new JPanel();
		listPane.setLayout(new BoxLayout(listPane, BoxLayout.PAGE_AXIS));
		JLabel label = new JLabel(labelText);
		label.setLabelFor(list);
		listPane.add(label);
		listPane.add(Box.createRigidArea(new Dimension(0,5)));
		listPane.add(listScroller);
		listPane.setBorder(BorderFactory.createEmptyBorder(10,10,10,10));

		//Lay out the buttons from left to right.
		JPanel buttonPane = new JPanel();
		buttonPane.setLayout(new BoxLayout(buttonPane, BoxLayout.LINE_AXIS));
		buttonPane.setBorder(BorderFactory.createEmptyBorder(0, 10, 10, 10));
		buttonPane.add(Box.createHorizontalGlue());
		buttonPane.add(cancelButton);
		buttonPane.add(Box.createRigidArea(new Dimension(10, 0)));
		buttonPane.add(setButton);

		//Put everything together, using the content pane's BorderLayout.
		Container contentPane = getContentPane();
		contentPane.add(listPane, BorderLayout.CENTER);
		contentPane.add(buttonPane, BorderLayout.PAGE_END);

		//Initialize values.
		setValue(initialValue);
		pack();
		setLocationRelativeTo(locationComp);
	}

	//Handle clicks on the Set and Cancel buttons.
	public void actionPerformed(ActionEvent e) {
		if ("Set".equals(e.getActionCommand())) {
			ListDialog.value = (String)(list.getSelectedValue());
		}
		ListDialog.dialog.setVisible(false);
	}
	
}
